Postulate for airtightness limits in large buildings

DIN 4108-7 requires a limit of q50 ≤ 3.0 m³/m²h for the air permeability of large buildings. Even stricter limits with respect to q50 can be found at DGNB [German Sustainable Building Council] and in the Swiss MINERGIE Standard.
It is the objective of this presentation to develop awareness of this topic in the audience and to give recommendations as to which limits can be applied to new building projects.
Theoretical considerations and experience from measurements lead to the conclusion that a volume-based limit of n50 is not a suitable target value for large buildings. Because of the changing surface-area-to-volume ratios (SA:V-ratio) in large buildings, it makes sense to require an envelope-based limit, especially since there are requirements for limiting air permeability for building component joints and service apertures. Existing limits and results from airtightness measurements are presented. The presentation will also outline the main points of the approach to achieving airtightness as planned.